GP's comment can of course be read more correctly as "the purpose of existing drug laws (in the US), ..."
Did all those countries also create those laws to harass certain populations?
I would concur much of the puritanism and authoritarianism around the world about drugs originates from the US, but hardly all of it.
More or less everyone I know has tried drugs (MJ, magic mushrooms, LSD) or does them on a regular basis, but I don't know anyone who's ever been arrested over it. What I'm saying is there doesn't seem to be (much) of a stigma against drugs, neither with the population, nor with the cops. Nevertheless, MJ is illegal, and the protests for legalization started soon after the ones in the US.